Cockroaches (Order Blattodea)

Australia has more than 400 species of native cockroaches that live in the bush. Most are harmless and some are even attractive. They range from fragile species around 3 mm long to the massive Giant Burrowing Cockroach, Macropanesthia rhinocerous, which can grow to a length of 6.5 cm and weigh as much as 20 grams.

The small number of pest species of cockroaches in Australia are all introduced and have given cockroaches a bad name.

The attractive Barred Cockroach, Cosmozosteria subzonata can be found foraging during the day in coastal areas from Gladstone, Queensland to northern New South Wales.

Most cockroaches are active, flattened insects with long spiny legs. Their heads are usually covered by an overhanging, shield-like thorax. Most adults have two pairs of wings with the front ones thickened. Quite a few species have wingless adults, as in the Giant Burrowing Cockroach.

The peculiar, very flattened shape of Trilobite Cockroaches (Laxta spp.) enables them to slip into very narrow spaces under loose bark and in rock crevices in open forest and rainforest in eastern Australia and south-west Western Australia.

The head of the Bush Cockroach, Methana marginalis, is covered by the shield-like thorax.

Cockroaches undergo gradual metamorphosis. Many eggs are usually laid within a tough, seed-like egg capsule (ootheca) that can sometimes be seen protruding from the tip of the abdomen of the female. Some species, such as wood and burrowing cockroaches, give birth to live young. Cockroach nymphs look similar to adults but lack wings and sometimes differ in colour and texture.

Most cockroaches are active at night, foraging on or near the ground. During the day they hide under bark, logs, and stones. Other cockroaches are burrowers, either in rotting logs or in the soil.

Some cockroaches are active during the day such as colourful species of Ellipsidion (Blattellidae) that can be found on leaves in bright sunlight.

Some cockroaches are active during the day such as colourful species of Ellipsidion (Blattellidae) that can found on leaves in bright sunlight.